Tension device for sewing-machin es



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TENSI ON DBVIGE FOR. SEWING MACHINES.

No. 488,508. Patented Dec. 20, L892.

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r A. 0. SPENCER. TENSION DEVIGE FOR SEWING MACHINES. No. 488,508.Patented Dec. 20, 1892.

ALVAH C. SPENCER, OF BOSTON, MASSACHUSETTS, ASSIGNOR TO THE GOOD- YEARSHOE MACHINERY COMPANY, OF HARTFORD, CONNECTICUT.

TENSION DEVICE FOR SEWING-MACHINES.

SPECIFICATION forming part of Letters Patent No. 488,508, dated December20, 1892. Application filed July 23, 1892- Serial No. 441,006- (Nomodel.)

To 61/ whom it may concern.-

Be it known that I, ALVAI-I G. SPENCER, of Boston, county of Suffolk,State of Massachusetts, have invented an Improvement in Sewing-Machines,of which the following description, in connection with the accompanyingdrawings, is a specification, like letters and figures on the drawingsrepresenting like parts.

This improvement in sewing machines re- Io lates more especially to thatclass of machine using waxed thread and employed for stitching leather,the particular part of the machine improved by me being that forcontrolling the delivery of the thread to the needle.

Figure 1, in side elevation represents a sufficient portion of a sewingmachine with my improvements added to enable my invention to beunderstood. Fig. 2, is a detail looking at the machine shown in Fig. 1from the left chiefly to show the devices employed to open the clampingjaws. Fig. 3, is a view of the clamping jaws looking down below the line00, Fig. 1. Fig. 4, is a much enlarged section in the line cc, Fig. 1,and Fig. 5, an enlarged View of the lever e. V

. The column A, the head frame A thereon; the main cam shaft A and thecam A are and may be all as common in United States Patent No. 412,704.,dated October 8, 1889.

The column has an attached bracket 13 which supports a wax pot B ofusual construction heated in usual manner by or through the pipes B BThe wax pot has erected upon it a post B on which are mounted theclamping jaws composed of two members a, a one being pivoted on theother at a a spring a acting normally to keep the jaws closed on thethread If, in its dry state and on its way into the wax pot from somesuitable spool, cop, or bobbin. The dry thread is led into the wax pot,under a roll therein, not shown, and thence out through a scraper andthe hollow screw 0. all as usual. The waxed thread goes from the screw adirectly to and about a rolling tension wheel b, mounted on a stud I)supported in the stand 12 The stud b has mounted on itlooselyalockingwheel cshown as toothed at its periphery. Surrounding asquared part of the stud b is a friction plate b acted upon by a spiralspring 17 made adjustable as to its effective strength by a nut 19* heldin place by a check nut 6 I shall preferably place felt or equivalentfriction washers, as 2, at each side the tension wheel.

On the head A on a stud d I have mounted a lockin g device shown asaleverd having a finger or plate (Z to engage the locking wheel 0, thefinger or plate as shown being shaped to enter the notches in the saidwheel a as shown by full lines Fig. 1 and restrain it from rotation solong as the main shaft is being turned in its forward directionindicated by the arrow near the wheel A in Fig. 1, the rotation of thetension wheel being then restrained frictionally by a force due to thespring and its adjustment. The short arm of the lever d has a lug 3, anda pivot l; and on the pivot is mounted a lever 6 shown in Figs. 1 and 5,the. latter figure showing the said lever much enlarged. The lever e isforked at its lower end to leave two lugs 5, 6, which cooperate with thelug 3 and prevent too great movement of said lever. The upper end of thelever e is also shown as forked to receive a pin 7 constituting a centerof motion or fulcrum of a brake block e'preferably having a concavedface covered with leather as e or with some other usual frictionsurface. The lever d has a lug 8 through which is extended or to whichis jointed a rod it connected 8o loosely but in an adjustable mannerwith an elbow lever h pivoted at 71. in ears 10, of the stand b Thelowerend of the elbow lever h is joined by link 72 with an ear of the jaw a,the construction being such that the raising of lever d will open theclamping jaws and leave the dry thread free to rend through them.

When the lever e occupies its full line position Fig. 1 which is itsposition when the cam wheel A is being rotated in its forward direc- 0tion the pin 7 is out of center-with relation to the center of the shaftA and the pivot 4. of the lever e, and in this condition the finger orplate 01 enters a notch in and holds wheel 0, and the rotation of thetension wheel is restrained to thus give tension tot-he waxed thread,and the clamping jaws are kept closed on the dry thread.

When the stitching of a shoe has been completed, the machine is stoppedwith the usual Ioo needle out of the shoe and at this time it is desiredto release the thread from tension so that as the shoe is removed thethread con nected to it at the last stitch may be pulled freely from themachine. To effect this the operator just after the machine has beenstopped will reverse the shaft A and wheel A for a slight distance, hehaving his hand on the usual hand-wheel, thus turning the wheel A in adirection opposite the arrow 12, such movement of the wheel A acting onthe brake block e and moving it to the left viewing Fig. 1 into itsdotted line position, and putting the pivot 7 in line with the center ofshaft A and pivot 4, thus turning the lever d into its dotted lineposition which results in removing the finger or plate 01 from the Wheel0 and in opening, as stated, the clamping jaws.

I do not broadly claim releasing the tension by reversing the shaft Anor do I broadly claim releasing both the tension wheel and jawssimultaneously, but I have produced a novel and simple mechanism foreffecting the release of the thread at the proper time.

Having described my invention WhatI claim and desire to secure byLetters Patent is:-

1. In a wax thread sewing machine, a tension wheel, a locking wheelagainst which it is held frictionaily, and the levers d and e, combinedwith a brake block, and the wheel A adapted only in its reverse rotationto act on said brake block and, move the said levers in a direction torelease the locking wheel, substantially as described.

2. In a wax thread sewing machine, a ten sion wheel, alocking wheelagainst which it is held frictionally, and the levers d and 6, combinedwith the wheel A adapted only in its reverse rotation to move the saidlevers in a direction to release the locking wheel, clam ping jaws forthe thread on its way to the wax pot, and connections between said jawsand the said lever d whereby the tension wheel and clamping jaws aremade to release the thread simultaneously, substantially as described.

8. The tension wheel, the locking Wheel notched at its periphery, thelever d having the plate d and the lever e pivoted on the lever d, andthe wheel A combined with a brake mounted upon the said lever e andadapted to be acted upon to move the lever d and effect the release ofthe locking wheel only upon the reverse rotation of the said wheel Asubstantially as described.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

ALVAH O. SPENCER.

Witnesses:

GEo. W. GREGORY, FRANCES M. NOBLE.

